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Fix planner to make a reasonable assumption about the amount of memory space

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used by array_agg(), string_agg(), and similar aggregate functions that use
"internal" as their transition datatype.  The previous coding thought this
took *no* extra space, since "internal" is pass-by-value; but actually these
aggregates typically consume a great deal of space.  Per bug #5608 from
Itagaki Takahiro, and fix suggestion from Hitoshi Harada.

Back-patch to 8.4, where array_agg was introduced.
This commit is contained in:
Tom Lane 2010-08-14 15:47:21 +00:00
parent d2945deefb
commit a5955f4a65
1 changed files with 13 additions and 1 deletions
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14
src/backend/optimizer/util/clauses.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.287 2010/03/19 22:54:41 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.287.4.1 2010/08/14 15:47:21 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -549,6 +549,18 @@ count_agg_clauses_walker(Node *node, AggClauseCounts *counts)
counts->transitionSpace += avgwidth + 2 * sizeof(void *);
}
else if (aggtranstype == INTERNALOID)
{
/*
* INTERNAL transition type is a special case: although INTERNAL
* is pass-by-value, it's almost certainly being used as a pointer
* to some large data structure. We assume usage of
* ALLOCSET_DEFAULT_INITSIZE, which is a good guess if the data is
* being kept in a private memory context, as is done by
* array_agg() for instance.
*/
counts->transitionSpace += ALLOCSET_DEFAULT_INITSIZE;
}
/*
* Complain if the aggregate's arguments contain any aggregates;